Epoxy-functional derivatives of epoxy resins are of interest in the industry as these derivatives can be useful to improve the properties of the curable epoxy resin formulations made from such epoxy-functional derivatives such as reduced volatility and reaction exotherm; and to improve the properties of the thermosets derived from these curable epoxy resin formulations such as increased flexibility and fracture toughness.
Epoxy-functional resins comprising the reaction products of an excess of bisphenol A diglycidyl ether and a primary (1°) monoamine (such as n-butylamine) are known in the prior art. However, these known epoxy-functional resins have a relatively poor balance of properties, i.e., one or more of the resins' properties such as heat resistance and melt viscosity may be inadequate for use in some applications.
Various polymers of divinylbenzene dioxide (DVBDO) including epoxy-functional resins comprising the reaction product of excess DVBDO and a polyamine such as diethylenetriamine are also disclosed in the prior art. For instance, Examples 24-28 of U.S. Pat. No. 2,912,389 disclose epoxy-functional resins. However, the epoxy-functional resins disclosed in U.S. Pat. No. 2,912,389 have a very high equivalent ratio of epoxide/amine groups (e.g., r=10) and the resulting epoxy-functional resins gel upon heating to greater than or equal to (≧) 120° C.